Circuit-switched networking has traditionally been used in telephony systems. In such circuit switched systems, a dedicated connection or physical path is established for a telephone call, the connection lasting the duration of the telephone call Voice communications over this dedicated connection provide real time connections, such as conventionally known person-to-person telephone calls.
In recent years, packet networks, such as Internet Protocol (IP) networks, have been used for the transport of data. These packet networks transmit data by segmenting the data into packets which are sent according to the priority of the data within the packets; thus, the individual packets are prioritized. At the receiving end, these packets are reassembled according to the assigned priority to reconstruct the data. Packet networks are conveniently able to transport data without having to create a dedicated connection between a originating gateway and a terminating gateway of the packet network; thus, providing an efficient use and allocation of network bandwidth.
Packet networks are recently being developed to transport voice data via packets, such as using Voice over Internet Protocol (VoIP), in addition to transporting data, i.e., providing multi-media data transport. The efficiency and flexibility of packet networks has made this technology very attractive for telecommunication and Internet service corporations throughout the world. Packetized data transport is highly dependent on packet prioritization to accomplish multi-media data transport effectively.
Current packet networks support multiple tiers of service types for the voice data transport. Each of these service types requires a relative guarantee of bandwidth matching the subscriber service type. A typical packet data voice call has two attributes: (1) the type of compression during the analog-to-digital conversion and (2) the priority the packets are sent. The type of subscriber is determined by these two attributes. A premium subscriber is guaranteed bandwidth irrespective of network resource conditions. A non-premium subscriber is allocated network resources on the best effort.
In most packet networks, voice packets are assigned the highest priority in order to ensure that the voice call occurs in real time. However, a significant number of subscribers use voice messaging services for unanswered voice calls to the subscriber. Voicemail has become a ubiquitous tool in businesses and is increasingly prevalent in many private residences and with wireless subscribers. For example, a voice call over the packet network is transported to a subscriber with the packets assigned the highest priority As such, when a packetized voice call goes unanswered, the voice call is re-routed to a voice messaging system (VMS), the voice packets having the same priority. The amount of voice messaging traffic is significant in most networks due to high voicemail subscription rates and the fact that the average voicemail message lasts about 2 minutes. Disadvantageously, transporting these voice calls to the voice messaging systems using the highest priority level results an inefficient use of network bandwidth since it is not necessary that these voice messaging systems receive the packetized voice calls in real time